US4285022A - Devices adapted to detect variations in magnetic flux notably circuit breakers - Google Patents

Devices adapted to detect variations in magnetic flux notably circuit breakers Download PDF

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Publication number
US4285022A
US4285022A US06/058,261 US5826179A US4285022A US 4285022 A US4285022 A US 4285022A US 5826179 A US5826179 A US 5826179A US 4285022 A US4285022 A US 4285022A
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United States
Prior art keywords
voltage
electret
electrodes
movable electrode
force
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US06/058,261
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English (en)
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Jacques Lewiner
Gerard Dreyfus
Didier Perino
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H83/00—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current
    • H01H83/14—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by imbalance of two or more currents or voltages, e.g. for differential protection
    • H01H83/144—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by imbalance of two or more currents or voltages, e.g. for differential protection with differential transformer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H59/00—Electrostatic relays; Electro-adhesion relays
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
    • H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
    • H02H3/33—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors using summation current transformers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H59/00—Electrostatic relays; Electro-adhesion relays
    • H01H2059/009—Electrostatic relays; Electro-adhesion relays using permanently polarised dielectric layers

Definitions

  • the invention relates to devices adapted to detect magnetic flux variations so that passage through a given threshold by the amplitude of such a variation per unit time is manifested by the movement of an element adapted to trigger an action such as a signal, an alarm or a safety operation, this element being notably the movable contact of an electrical switch.
  • the flux variation concerned is produced by a single and non-repetitive phenomenon, such as, for example, the translation of a magnet or the sudden variation of a direct current
  • the value of the induced electromotive force is directly proportional to the amplitude of the phenomenon to be detected.
  • the phenomenon to be detected is an alternating current of frequency f
  • the invention relates among others to circuit breakers or safety equipment mounted in the supply of an electrical circuit and designed to cut automatically or "cut-off" this supply from the appearance of a leakage current and/or of an overintensity at any point of said circuit.
  • Such circuit breakers are particularly advantageous for the detection of a leakage current corresponding to a portion of a supply current, which portion, coming from the source to the level of the receiver by following one of the two leads of a supply cord, returns to ground and not to the second lead of said cord through a human body placed involuntarily in contact with a bare conductive portion of the circuit concerned, which creates a particularly serious risk of electrocution in a moist environment.
  • Detection devices of the kind concerned according to the invention are of the type comprising an almost closed electrical circuit, such as a winding, arranged and mounted so that the variations of the magnetic flux to be detected generate by induction at the terminals of this winding an electrical voltage V, and they are characterized in that they comprise in addition two electrodes forming a capacitor, of which one is movable with respect to the other, an electret, interposed between these two electrodes, of which the charge produces a field exerting on these electrodes an electrostatic force H tending to bring them mutually together, means for forming from the above voltage V a rectified voltage U and to apply it between the two electrodes in a direction such that the field which results therefrom is opposed to that generated by the electret and hence tends to reduce the force H, and means urging "scarcely reversibly" the movable electrode in the direction opposite to the force H, the urging force of these means and the charge of the electret being selected so that the overshoots by the voltage U of a
  • the urging means with scarcely reversible action are of the magnetic type and constituted preferably by a fixed permanent magnet and by a part of magnetic material connected to the movable electrode,
  • the urging means with scarcely reversible action are constituted by an elastic mechanism with dead center overshoot,
  • a manual resetting member is provided to replace the movable electrode in its initial resting position after its swings
  • the detector device comprises, mounted on one of the leads connecting the output from the rectifying means to the capacitor, a voltage limiter adapted to cut-off this lead when the voltage U remains lower than the threshold U o and a high resistor connected between the two electrodes of the capacitor,
  • the detector device is a circuit breaker sensitive to unbalances of an electrical supply provided through first leads, and it comprises a transformer arranged so as to generate a voltage automatically in another lead on the appearance of such an unbalance in said supply, said voltage playing the role of the above voltage V, and an electrical switch mounted on one at least of said first leads and arranged so as to be opened by the abovesaid swings of the movable electrode,
  • the circuit breaker according to the previous paragraph is immaterially sensitive to a leakage current adapted to unbalance an electrical supply provided through at least two leads, or to an over-intensity appearing in one of these leads, and it comprises to this end two sub-assemblies upstream with a transformer and rectifier each sensitive to one of these faults and selected so as to form respectively control signals of the same order of magnitude, and a common downstream sub-assembly comprising the electret capacitor, the scarcely reversible return means and the switch,
  • the assembly of the transformer, the rectifying means of the voltage V, the electrodes, the electret, the urging means with scarcely reversible action and the switch are mounted in the same casing,
  • the casing according to the preceding paragraph is that of an electrical plug with at least two male or female pins
  • the casing according to the paragraph before last is a connector for an electrical plug comprising at least two male pins and at least two female pins.
  • the invention comprises, apart from these main features, certain other features which are preferably employed at the same time and which will be more explicitly considered below.
  • FIG. 1 of these drawings shows one use of an embodiment of a circuit breaker according to the invention.
  • FIG. 2 shows such a circuit breaker, diagrammatically.
  • FIG. 3 is the electrical diagram of a portion of another embodiment of such a circuit breaker.
  • FIG. 4 shows the circuit diagram of an improvement in these various circuit breakers.
  • FIG. 5 is a general schematic circuit diagram of the invention.
  • the circuit breaker shown in FIGS. 1 and 2 is contained in the casing 1 of an electrical plug with two male pins 2 and 3 connected electrically, through respectively two conductive leads 4 and 5, to an electrical apparatus 6.
  • This apparatus 6 is designed to be used in an environment where risk of electrocution exists, notably in a bathroom, a kitchen, a workshop or the like.
  • the reference numeral 7 is denoted the body of such a person partly immersed in water 8 of a bath 9, and whose left hand comes into contact with a bared area of one of the wires 4 and 5: the arrowed path 10 denotes the course of the leakage current which is then created through the body 7 and the pipes serving the bath 9 to ground, only a portion of this supply current which has come from the source to the point of use through the wire 4 (phase) returning to this source through the wire 5 (neutral).
  • the circuit breaker according to the invention is arranged so as to cut-off immediately one at least of the two wires 4 and 5 at the level of the plug 1 on the creation of such a leakage current.
  • a differential transformer 11 (FIG. 2), composed of three windings mounted on the same closed magnetic core 12, such as a ring of ⁇ -metal, namely two identical windings 13 and 14 constituted respectively by sections of two wires 4 and 5, and a third winding 15,
  • a capacitor composed of a fixed electrode 16 and a movable electrode 17, with the interposition of an electret 18, that is to say of a dielectric sheet charged electrically, secured to the fixed electrode 16, the charges of this electret, producing a field which exerts on the movable electrode 17 an electrostatic attractive force H tending to flatten it against the electret,
  • a switch 22 interposed in one at least of the two wires 4 and 5 so that it is closed as long as the movable electrode is flattened against the fixed electrode and on the contrary opened for the other stable position of this movable electrode, spaced from the fixed electrode.
  • the charge of the electret 18 and the force of the member 21 with scarcely reversible action are selected so that the swings of the movable electrode 17 from its vigilant (monitoring) or rest position (shown in FIG. 2) for which the switch 22 remains closed, to its active position for which it opens the switch 22 are ensured as soon as the value of the voltage U exceeds a predetermined threshold U o .
  • this threshold U o is selected to correspond with the maximum current I o tolerable for the leakage current defined above.
  • the rectifying bridge 20 is a full wave rectifier and if the voltage V is an alternating voltage with a frequency of 50 cycles, the response time of the circuit breaker is less than 100th of a second.
  • the switch 22 could be made double pole and cut these two leads simultaneously.
  • the electret 5 is advantageously constituted by a thin sheet of a polymer based on a fluorinated polymer or a substituted polyolefine of thickness comprised between 1 micron and 1 cm.
  • Its surface charge density may be comprised between 10 -12 Cb/cm 2 and 10 -4 Cb/cm 2 .
  • This member 21 is hence not constituted by a simple mechanical return spring.
  • said member 21 is constituted by a fixed permanent magnet adapted to close its magnetic circuit inside an armature 23 of magnetic material forming part of the movable electrode 17 or inserted on the latter.
  • the magnetic attractive force between the magnet and the movable electrode becomes a maximum at the end of stroke of the latter, which ensures firm maintenance of the latter in its end-of-stroke position as well as of the switch 22 in its open position.
  • the attracting member 21 could be constituted by a dead center overshoot elastic mechanism coupled to the movable electrode 17.
  • the resetting concerned could be produced by other than mechanical means, for example by temporarily applying to the terminals of the electrodes 16 and 17 a DC voltage of sufficient amplitude and opposite direction to the above voltage U.
  • said resetting can also be ensured by inserting a magnetic wedge between this magnet and this armature, so as to close the corresponding magnetic circuit by short-circuit, or, better still, by applying to the whole of the circuit breaker an external magnetic field opposite in direction to that exerted on the armature 23 by the magnet 21 and of sufficient intensity.
  • the latter modification is particularly advantageous when the group of components of the circuit breaker is enclosed in a common casing such as the housing 1 above.
  • circuit breaker could be mounted in a housing other than that of a free plug connector with male pins, for example in a fixed socket connector with female pins installed in a bath-room or a kitchen, or again in the housing itself of a portable electrical device whose use it is desired to render non-dangerous.
  • the circuit breaker is mounted in an independent housing forming a connector and itself including for this purpose two male pins and two female pins, this connector being connectable separately in a fixed outlet and able to receive in its turn a portable electric plug associated with one of the above electrical devices.
  • the circuit breaker is again sensitive to the appearance of a leakage current on one of the two leads 4 and 5, which appearance is detected as previously by the creation of a voltage induced in the winding 15, and then by its rectification by means of the bridge 20 and by its application to the terminals of the capacitor 16, 17 with the electret 18.
  • the circuit breaker concerned comprises a second transformer 25 composed of two windings mounted on the same closed magnetic core 26 such as a ring of ⁇ -metal, namely a first winding 27 constituted by a section of wire 5 (or 4) and a second winding 28.
  • This latter winding 28 is connected, like the previous winding 15, through a circuit 29 comprising a rectifying bridge 30, to the terminals 16 and 17 of the capacitor.
  • the number of turns of the secondary winding 28 is given a much smaller value than that of the secondary winding 15 in order that the voltage signals applied to the capacitor and corresponding to the triggering of the latter may be substantially identical, whatever the fault, (leakage current or excessive current) which gives rise to them.
  • the first channel must ensure triggering for leakage currents of the order of only some milliamperes whereas the excess currents detectable by the second channel are rather of the order of some amperes.
  • FIG. 3 It is also seen from FIG. 3 that there is a capacitor shunted across the output terminals of the rectifying bridge 30 and two rectifiers 32 and 33 connected in series respectively with the two bridges 20 and 30, which elements enable a time delay to be inserted in the tripping of the device of the order notably of some microseconds and thus to avoid these trippings being due to the simple appearance of ephemeral interference in the supply, in particular as regards the detection of excessive currents.
  • FIG. 4 there is shown diagrammatically an improvement consisting of providing, in the assemblies described above:
  • a locking member 34 (spark gap, Zener diode, . . .) inserted between one of the terminals of the rectifying bridge (20 or 30) and one of the electrodes 16 and 17 of the capacitor, the resistance of which member preserves a high value Z as long as the voltage U applied at its input remains less than U o , and is lowered on the contrary to a relatively low value z from the passage through this value U o by the voltage U,
  • a resistor 35 of a value comprised between z and Z (for example 100 megohms if z and Z equal respectively 10 and 1000 megohms) connected to the terminals of this capacitor 16, 17.
  • circuit breakers have a certain number of advantages with respect to those previously known.
  • they are not then arranged so as to consume any electrical current, even in their surveillance state, they are particularly easy to reset, after tripping, without necessitating the replacement of any part such as a fuse, their operation is particularly safe considering that the positions of their movable electrodes corresponding respectively to the two states of surveillance and of cut-off are remarkably stable and insensitive to shocks: the latter advantage is particularly valuable when the circuit breakers concerned are mounted in portable housings.
  • the transformer intended to detect a possible unbalance of such a supply, then with three phases, being then arranged so as to generate a voltage in its secondary equal at any moment to the algebraic sum of its three phases.
  • the invention encompasses all cases, shown diagrammatically in FIG. 5, where it is desired to detect the overshoots of a given threshold by the rate of change of a phenomenon P (FIG. 5) - and in particular by the sufficiently rapid appearance of such a phenomenon -, the change concerned being suitable to be manifested itself by a variable magnetic flux ⁇ , instantaneously generating in a winding E (of the type notably of windings 15 and 28 above) an induced electromotive force V, this electromotive force being then converted into a voltage U by rectification (at 20 and/or 30), then applied to a capacitor 16, 17 with an electret 18, so as to cause one of the electrodes of this capacitor to swing over, itself urged by a magnet 21 or the like, the swings concerned being then exploited for any desirable purpose, notably by the actuation of an electrical switch 22.
  • the means utilized for this exploitation which are shown diagrammatically in FIG. 5 by the block X, are advantageously arranged so as to react on the phenomenon P, as as been shown diagrammatically by the arrow R, so as at least to neutralize the possible dangerous effects capable of being caused by this phenomenon when its manifestation exceeds a certain magnitude.
  • Such other phenomena are for example, the movements of an object connected either to a magnet close to the winding E, or to a magnetic shield arranged at least in part between this winding E and a magnet close to the latter: such an object could, for example, be a float, which permits the detection of a level through a fluid-tight and magnetic wall.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Breakers (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Measuring Magnetic Variables (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
US06/058,261 1978-07-25 1979-07-17 Devices adapted to detect variations in magnetic flux notably circuit breakers Expired - Lifetime US4285022A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7822016A FR2432236A1 (fr) 1978-07-25 1978-07-25 Perfectionnements aux disjoncteurs sensibles aux courants de fuites
FR7822016 1978-07-25

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US4285022A true US4285022A (en) 1981-08-18

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US06/058,261 Expired - Lifetime US4285022A (en) 1978-07-25 1979-07-17 Devices adapted to detect variations in magnetic flux notably circuit breakers

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US (1) US4285022A (fr)
EP (1) EP0007868A1 (fr)
JP (1) JPS5518899A (fr)
CA (1) CA1131696A (fr)
FR (1) FR2432236A1 (fr)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4345223A (en) * 1980-10-28 1982-08-17 Chien Chun Yu Fuseless safety magnetic plug
US4378579A (en) * 1980-11-07 1983-03-29 Sprague Electric Company Alternately low and high input-impedance detector for use in a GFI
US4687906A (en) * 1983-11-15 1987-08-18 Matsushita Electric Works, Ltd. Portable electric hair dryer with electric shock protection circuit
US4931894A (en) * 1989-09-29 1990-06-05 Technology Research Corporation Ground fault current interrupter circuit with arcing protection
US5426552A (en) * 1991-07-08 1995-06-20 Aditan, Inc. Electrical supply safety socket
US5475557A (en) * 1988-12-16 1995-12-12 Solar Wide Industrial Ltd. Method and apparatus for protecting electrical systems
US5485340A (en) * 1991-07-08 1996-01-16 Aditan, Inc. Electrical supply safety plug
US5506455A (en) * 1992-05-06 1996-04-09 International Business Machines Corporation Electrical appliance with reduced electric field emissions
US6211684B1 (en) * 1998-12-28 2001-04-03 General Atomics Internal unbalance detection in capacitors
EP1202397A1 (fr) * 2000-10-25 2002-05-02 Brosco, Silvia Connecteur électrique à fiche équipé d'un interrupteur de securité incorporé pour des appareils électriques
US20040145446A1 (en) * 2003-01-27 2004-07-29 James Chou Overload prevention plug structure
US20110167617A1 (en) * 2008-07-04 2011-07-14 Saint-Gobain Glass France Method for electrically securing an electrical power supply of an electrically controlled lighting system or system with variable optical properties and use of the electrically secured system
US20150002984A1 (en) * 2013-06-28 2015-01-01 Weng Hong Teh Method of forming a magnetic mems tunable capacitor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62100353A (ja) * 1985-10-29 1987-05-09 Oki Electric Ind Co Ltd プリンタの紙送り機構

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2885511A (en) * 1957-04-15 1959-05-05 Erdco Inc Electrostatic relays
US3123742A (en) * 1959-06-08 1964-03-03 Moser
US3599043A (en) * 1967-12-19 1971-08-10 Uninorm Anstalt Electrical circuit breakers
US3813579A (en) * 1970-11-09 1974-05-28 Rucker Co Electric receptacle assembly with ground fault protection
US3857096A (en) * 1971-12-27 1974-12-24 L Gregory Electrical current leakage detector
US4015169A (en) * 1975-03-14 1977-03-29 Westinghouse Electric Corporation Two pole ground fault circuit interrupter with improved rectified supply and transient suppression for a trip circuit
SU601771A1 (ru) * 1976-02-05 1978-04-05 Предприятие П/Я В-8754 Электростатическое реле

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1053639B (de) * 1956-08-13 1959-03-26 August Stuke Schaltungsanordnung zum Schutz elektrischer Anlagen
FR1335118A (fr) * 1962-07-05 1963-08-16 élément de connexion de sécurité pour lignes électriques basse-tension
FR1407271A (fr) * 1964-06-20 1965-07-30 Electronique Et D Automatique Dispositif de protection des circuits électriques
US3376477A (en) * 1965-12-06 1968-04-02 Hubbell Inc Harvey Protective circuit
AR192614A1 (es) * 1971-02-04 1973-02-28 Elettrocondutture Dispositivo de seguridad para instalaciones electricas,del tipo electromagnetico diferencial,contra corrientes de dispersion a tierra
FR2294535A1 (fr) * 1974-12-10 1976-07-09 Lewiner Jacques Perfectionnements aux dispositifs de commande du genre des relais
FR2389896B1 (fr) * 1977-05-05 1981-07-10 Dreyfus Gerard

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2885511A (en) * 1957-04-15 1959-05-05 Erdco Inc Electrostatic relays
US3123742A (en) * 1959-06-08 1964-03-03 Moser
US3599043A (en) * 1967-12-19 1971-08-10 Uninorm Anstalt Electrical circuit breakers
US3813579A (en) * 1970-11-09 1974-05-28 Rucker Co Electric receptacle assembly with ground fault protection
US3857096A (en) * 1971-12-27 1974-12-24 L Gregory Electrical current leakage detector
US4015169A (en) * 1975-03-14 1977-03-29 Westinghouse Electric Corporation Two pole ground fault circuit interrupter with improved rectified supply and transient suppression for a trip circuit
SU601771A1 (ru) * 1976-02-05 1978-04-05 Предприятие П/Я В-8754 Электростатическое реле

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4345223A (en) * 1980-10-28 1982-08-17 Chien Chun Yu Fuseless safety magnetic plug
US4378579A (en) * 1980-11-07 1983-03-29 Sprague Electric Company Alternately low and high input-impedance detector for use in a GFI
US4687906A (en) * 1983-11-15 1987-08-18 Matsushita Electric Works, Ltd. Portable electric hair dryer with electric shock protection circuit
US5475557A (en) * 1988-12-16 1995-12-12 Solar Wide Industrial Ltd. Method and apparatus for protecting electrical systems
US4931894A (en) * 1989-09-29 1990-06-05 Technology Research Corporation Ground fault current interrupter circuit with arcing protection
US5485340A (en) * 1991-07-08 1996-01-16 Aditan, Inc. Electrical supply safety plug
US5426552A (en) * 1991-07-08 1995-06-20 Aditan, Inc. Electrical supply safety socket
US5506455A (en) * 1992-05-06 1996-04-09 International Business Machines Corporation Electrical appliance with reduced electric field emissions
US6211684B1 (en) * 1998-12-28 2001-04-03 General Atomics Internal unbalance detection in capacitors
EP1202397A1 (fr) * 2000-10-25 2002-05-02 Brosco, Silvia Connecteur électrique à fiche équipé d'un interrupteur de securité incorporé pour des appareils électriques
US20040145446A1 (en) * 2003-01-27 2004-07-29 James Chou Overload prevention plug structure
US20110167617A1 (en) * 2008-07-04 2011-07-14 Saint-Gobain Glass France Method for electrically securing an electrical power supply of an electrically controlled lighting system or system with variable optical properties and use of the electrically secured system
US8336189B2 (en) * 2008-07-04 2012-12-25 Saint-Gobain Glass France Method for electrically securing an electrical power supply of a system with variable optical properties
US20150002984A1 (en) * 2013-06-28 2015-01-01 Weng Hong Teh Method of forming a magnetic mems tunable capacitor

Also Published As

Publication number Publication date
FR2432236A1 (fr) 1980-02-22
EP0007868A1 (fr) 1980-02-06
FR2432236B1 (fr) 1981-12-24
CA1131696A (fr) 1982-09-14
JPS5518899A (en) 1980-02-09

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